People may ordinarily think of insects as creatures that live on the ground or in the air. However, a number of insect species spend at least part of their life cycles living underwater, for example, in streams or lakes. The presence or absence of these insects (along with some other aquatic invertebrates) are often used as indicators to estimate water quality. For those interested in learning how to identify these aquatic macroinvertebrates, this free digital atlas offers an interactive taxonomic key containing "an online collection of 150 specimens representing 9 orders of benthic macroinvertebrates" that live at the bottom of water bodies in eastern North America. Rather than the line drawings commonly used in this type of key, this atlas uses photographs of specimens. Readers can explore the key by clicking first on any of the nine orders of macroinvertebrates, which lead to the families within each order, and from there users can select an individual species. At all three levels, an explanatory overview and diagnostic characteristics are provided in the right sidebar, with highly detailed, zoomable images available at the species level. It should be noted that this resource is not mobile-optimized and is best suited for use on a computer. This atlas is part of Learning to See, Seeing to Learn, a multi-institution interdisciplinary project led by researchers at Carnegie Mellon University and the University of Pittsburgh.